Parkinson's disease is an inexorably progressive disorder of unknown cause in which neurons of the substantia nigra progressively degenerate resulting in ever greater degrees of brain dopamine deficiency. While a number of treatments have been developed that improve the neurochemical deficit, no treatment has been demonstrated in humans that delays the progression of the disease (as distinguished from masking symptoms). Such an effect is highly desirable because if this could be achieved, a significant delay in clinical deterioration of patients could be realized. This competitive continuation proposal aims to continue UT Southwestern Medical Center as a Clinical Site for ongoing conduct of the NET-PD clinical trials. These include the ongoing LS-1 study and FS-ZONE study. LSI is a 5 year double-blind, placebo controlled investigation of creatine as a possible disease-modifying agent for PD. FS-ZONE is a 44 week futility trial assessing pioglitazone as a possible disease-modifying agent for PD. UT Southwestern Medical Center in Dallas, TX is well suited to continuing its work as a Clinical Site of the NET-PD network. It functions as the primary academic referral center for North Texas, and its four staff neurologists are experienced in the design, conduct, and reporting of clinical trials in Parkinson's disease. If funded, the site will continue its active follow-up of te 49 subjects currently enrolled in the NET-PD LS1 trial and will continue to recruit and follow subjects for the ongoing FS-ZONE study. While it is unclear if either agent under study will slow the progression of PD, this unique network of clinical research centers is ideally suited to perform large scale, long duration, scientifically sound clinical trials that have great promise fo ultimately discovering a drug or drugs that can slow the degenerative process of PD.